“I am disappointed by this turn of events, and hope this is not a sign of how your agency will proceed on this matter,” Broun wrote EPA Administrator Lisa Jackson on Friday. “As Chairman of the Investigations and Oversight Subcommittee of the Science, Space, and Technology Committee, I am very interested in the manner in which this scientific review was conducted.”

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At issue is the Pebble Mine, which could yield substantial amounts of copper, gold and molybdenum, which is used in alloys.

Republicans and mining groups are concerned that EPA might use the test to kill the mine even though developers have not yet filed a blueprint. They say that would be unprecedented — and possibly illegal — and could scare away mining and manufacturing projects near waterways.

Mine opponents, which include commercial fishermen, native tribes, environmentalists and some state lawmakers, asked the EPA to do the test because they say the mine developers have intentionally withheld a formal application for years.

They say the developers, Pebble Limited Partnership, are waiting for the right political situation because any mine would be unfeasible for Bristol Bay’s sockeye salmon, which accounts for almost half the world’s supply.

Last month, Oversight Republicans in the House also pressed EPA for a briefing. It gave the agency until Oct. 8 to hand over documents related to the watershed test.